“HAPPY Z DAY.” That’s the birthday message Taylor Swift left on Instagram for the now 24-year old Zayn Malik on Thursday (Jan. 12).

The note may offer a sneak peek of a new project the pair have been working on. The two pop superstars teamed up for a track on the Fifty Shades Darker soundtrack, and there is speculation that the image accompanying the post features a still from a music video for their song, “I Don’t Wanna Live Forever.” And just last week reports surfaced that the two had damaged a London hotel room during the making of a video.

Malik recently credited his girlfriend Gigi Hadid for initiating the collaboration with Swift. In a radio interview, the former One Directioner shared, “The interesting thing was she’s actually friends with Gi, so she already reached out because [producer] Jack [Antonoff] had just played her the song anyway. She mentioned to me that she liked the song so I already kind of knew in the back of my head that she liked it so I asked her if she wanted to be on it and she was cool with it.”

With Fifty Shades Darker hitting theaters February. 10, the “I Don’t Wanna Live Forever” video should be on the way soon.